DESCRIPTION: The overall goal of this project is to develop a novel ambulatory, easy-to-administer, short-duration, and highly quantitative method of evaluating/screening an individual for excessive sleepiness, as well as his/her propensity for developing sleep-disordered breathing (i.e., sleep apneas/hypopneas). The proposed Ambulatory Sleepiness & Apnea Propensity (ASAP(tm)) evaluation system is a paradigm change in terms of the entire screening/assessment method for the presence of sleep-disordered breathing and excessive sleepiness that affect millions (prevalence of Obstructive Sleep Apnea, OSA, alone is around 4%). It is an innovative approach that simultaneously produces two indices related to (1) excessive daytime sleepiness, and (2) the likelihood of demonstrating respiratory disturbances during sleep, by combining the highly quantitative information acquired during a short duration (approximately 15 minute) Maintenance of Alertness Test (MAT) with a novel analysis of the wake to sleep transition (both neurological and respiratory signals) during a short duration (approximately 30 minutes) subsequent nap. Thus, the "Alertness Index" provided by MAT is combined with the "Sleepiness Index" obtained from the subsequent nap to produce an overall "Excessive Daytime Sleepiness Index". The nap also produces an overall "Apnea-Propensity Index" by a novel and automatic analysis of respiratory variability around the start of sleep onset period. The applicants have provided preliminary analysis of PSG data from patients with a variety of OSA severity (normal, mild, moderate, and severe) showing that the Apnea-Propensity Index, computed around the first wake-sleep transition, demonstrates good correlation (Correlation Coef.=86%) with the clinical indicator of severity of OSA (Apnea/Hypopnea Index, computed from the entire night PSG). The proposed ASAP(tm) system can be conveniently utilized in many locations ranging from sleep laboratories to a psychiatry and neurology office/clinic, primary care physician's office, and health-care stations within workplace. Phase I of this project will focus on developing the hardware/software component of ASAP(tm), as well as its innovative algorithms for EDS and apnea screening/monitoring. The system will also undergo an extensive clinical evaluation at a sleep disorders center with both normal and OSA patients.